Cycles Render grainy despite many samples?
Check "Square Samples", otherwise Blender will use -exactly- the number of AA samples as you type in. 700 unsquare AA samples is around 27 square samples.

The blend file you provided has it set at 100 AA samples, which is barely preview quality.

Additionally, you have some REALLY strange material shaders. Theres a fresnel node plugged directly into a color node. A ray path node directly in an add shader node. You mix glossy and glass shaders.
Its really strange, i've never seen shader setups like this.

Last thing: you built a closed box and put objects inside with indirect light, this gives you huge amounts of bounce light, which creates loads of noise. If you get a HDR instead you can get better results with way less bounce and noise than this approach.